Currently the liquid crystal displays (LCDs) have been dominating in almost all the major display markets for several applications, such as monitors, mobile phones, televisions, notebook computers, tablet personal computers (PCs), global positioning system (GPS) devices, portable video players, as the technologies of the LCD have been developing widely, deeply and quickly.
The liquid crystals play the role of light valves to control the light transmission and the light blocking at instantaneous display time in each pixel of the LCD. In the view of the control mechanisms of the liquid crystals, the LCD can be divided into the types of the vertical alignment (VA) and the plane switching.
The VA type can be further divided into several sub-types. Generally, the VA type LCD has very fast response time for the liquid crystals, and is especially suitable for displaying the video showing very fast movements. However, when the user presses the LCD screen by fingers or other objects, the vortex-shaped pattern appears at the place being pressed on the screen of the LCD, because the interval of the vertical alignment of the liquid crystals are shortened by such vertically pressing on the screen. In this aspect, the VA LCD is not suitable to be used for the touch-panel display, since the screen of the touch-panel display tends to be frequently touched and pressed by the user's finger, and the displayed picture thereof will be blurred at anywhere is being touched.
On the other hand, the plane switching type LCDs, including the in-plane switching (IPS) and the fringe field switching (FFS) LCDs, do not have this kind of problem, and provide good performance for the touch-panel display, since the liquid crystal alignments thereof occur in the plane (horizontal) direction rather than the vertical direction. Generally, FFS LCD has larger aperture ratio and transmittance than those of IPS LCD, and makes itself as a good candidate for the portable touch-panel display. However, the charging time for the counter electrode in each pixel of the typical FFS LCD is not short enough, and results in the long response time.
Please refer to FIG. 1, which show a top view of a pixel in an FFS LCD in the prior art. In FIG. 1, the pixel electrode 66 consists of the body 66a and strips 66b, while the counter electrode 63 is a plane electrode. Since the area of the counter electrode 63 almost covers the entire pixel, therefore the capacitance of the counter electrode to be charged is large. Accordingly, the capacitance charging time for the counter electrode is long, and the response time may not be short enough for the video display.
Please refer to FIG. 2, which show a top view of a pixel in an FFS LCD in the prior art. In FIG. 2, the pixel electrode 76 consists of the body 76a and strips 76b; while the counter electrode 73 consists of the body 73a and strips 73b. It can be seen from FIG. 2 that the strips 73b of the counter electrode 73 interleave the strips 76b of the pixel electrode 76 from the top view. That is to say, each of the strips 73b of the counter electrode 73 is located in the projection of the spacing between two adjacent strips 76b of the pixel electrode 76. Although the capacitance of the counter electrode 73 in FIG. 2 is lower than that in FIG. 1 due to the smaller area of the counter electrode 73 in FIG. 2 than that in FIG. 1, the strip structures of the counter electrode 73 and the pixel electrode 76 in FIG. 2 cause the difficulty in the assembly of these two electrodes, since the strips 73b of the counter electrode must perfectly interleave the strips 76b of the pixel electrode to generate the uniform desired electrical field for rotating the liquid crystals. The slight position shift between the pixel electrode and the counter electrode will result in the slight shift in the alignment of the liquid crystals, which however will catastrophically and tremendously decrease the contrast ratio of the LCD due to the light leaking, since the contrast ratio is defined as the maximum brightness divided by the minimum brightness.
For overcoming the above-mentioned drawbacks existing in the conventional techniques, the novel FFS LCD apparatuses are provided in the present invention with the advantages of short charging time and excellent display performance.